One commercial source of common salt (sodium chloride) is wells containing underground brine pools in which water is substantially saturated with salt. Salt is generally obtained from these brine pools by pumping the brine from underground and evaporating water to yield solid, dry salt. While lower grade salts may be obtained by natural evaporation of brine held in ponds, high purity salt is commonly obtained by a process in which the brine is boiled to remove the water. A substantial cost of producing salt is incurred when the brine is boiled off, since the brine has a specific heat of 0.78 cal/g.degree.C. and water has a specific heat of vaporization of 540 cal/g. Using these figures, the energy expended in producing salt from saturated brine at 22.degree. C. can be calculated as follows: The heat required to raise the temperature of 100 g of the brine from 22.degree. C. to 108.7.degree. C. (the boiling point of brine) is 100 g.times.0.78 cal/g.degree.C..times.(108.7-22).degree.C.=6762 cal. The heat required to vaporize the water is 73.6 g (the amount of water in 100 g of saturated brine).times.540 cal/g.=39744 cal. The total heat used to evaporate the water is 46,506 cal. and 26.4 g of salt is obtained. Thus 1761.6 cal. (46,506/26.4) are expended in producing each gram of salt.
It is a primary object of the present invention to provide a method of obtaining high purity salt from brine that requires the input of substantially less energy than is required to boil water from brine.